What are mutable arrays in JavaScript?

What are mutable arrays in JavaScript?

In JavaScript, arrays are mutable, meaning you can change their contents after creation. You can add, remove, or modify elements.

Can you give me an example of modifying an array?

Sure! You can use methods like push() to add an element or splice() to remove elements. For example: let arr = [1, 2, 3]; arr.push(4); // arr is now [1, 2, 3, 4].

What happens if I try to access an index that doesn't exist?

If you access an index that doesn't exist, it will return undefined. For example, arr[5] will return undefined if the array has less than 6 elements.

Are there any methods to copy an array?

Yes! You can use slice() to create a shallow copy or the spread operator [...]. For example: let newArr = arr.slice(); or let newArr = [...arr];.